When you install Vista SP1, a backup of all replaced files is made. This is done so you can roll back to pre-SP1 if you desire. SP1 has been out for some time now and many of you will no doubt be satisfied with using it. In this guide, you will learn how to reclaim disk space taken up by the Vista SP1 install.
How to reclaim disk space after SP1 install
By following this guide, you will be able to save 600-800 MB of disk space.
Please note: After running this tool, you cannot uninstall Vista SP1.
Type vsp1cln.exe and hit enter.
When prompted, type Y and hit enter.
After a few seconds, you will have your hard disk space back.